The priority application Number Japanese Patent Application No. 2003-434796 upon which this patent application is based is hereby incorporated by reference.
1. Field of the Invention
This invention relates to a head-up display device. In more detail, this invention relates to the head-up display device including a display unit for displaying information; a reflector supported by a rotational shaft; and an adjuster for adjusting a rotational position of the reflector by a gearing system. The gearing system so adjusts the rotational position of the reflector that the reflector may reflect light of the information from the display unit toward a projection area on a windshield of a vehicle, for allowing a vehicle driver to see both a front view through the windshield and a superimposed reflected image of the information.
2. Description of the Related Art
In recent years, a head-up display device (HUD) has come into use in a driving position of a vehicle, a train, and the like, as information requested by a driver while driving has been increased and diversified. The HUD displays critical information as a reflected image on a windshield of a vehicle to allow the driver to see a front view through a windshield and a superimposed reflected image.
In such an HUD system, a display unit is provided inside an instrument panel of the vehicle, and a reflector, such as a magnifying mirror, reflects light, which contains information, from the display unit toward a projection area on such as a windshield or a combiner. Thus, the vehicle driver sees a view through the projection area and a reflected image superimposed on the projection area.
Meanwhile, drivers have various eye points (viewing positions) according to their sitting heights. When the reflected light is not reflected toward the eye points of the drivers at the projection area, the drivers cannot see superimposed information adequately. For solving this problem, an HUD having an adjuster to adjust a position of a reflector is disclosed in Published Japanese Patent No. 2645487. In the HUD disclosed in this document, the driver adjusts the reflector with the adjuster to see the superimposed reflected image.
In addition, another HUD is disclosed in Japanese Patent Application Laid-open No. 2001-97073. In the HUD disclosed in this second document, corresponding to an engine shutdown, a rotational position of a reflector is so adjusted to prevent sunlight falling through the windshield from being retroreflected toward a display surface of the display unit.
In the conventional HUDs as described above, a mechanism for rotating a rotatable reflector around a rotational shaft by transmitting power from a gearing system is provided. However, since a narrow gap (backlash) exists for driving a gear smoothly, when the vehicle vibrates, the reflector vibrates and visibility of the reflected image is reduced. In particular, as disclosed in the second document, when using a plurality of gears for rotating the reflector (mirror), the backlash increases and the reflector vibrates easily.
Further, in recent years, the reflector has been larger as the display unit has become larger, and the larger reflector is easier to vibrate. The reflected image projected on the projection area also has been enlarged, and the visibility of the reflected image is reduced further. Therefore, there is a problem to prevent the reflector from vibrating with a simple configuration.
Accordingly, it is an object of this invention to provide a head-up display device of which the reflector is prevented from vibrating owing to the backlash.